The third generation partnership project (3GPP) has developed a specification for advancements in wireless telecommunication systems commonly known as Long Term Evolution or LTE. LTE has many improvements and advancements over the previous generations of wireless telecommunication networks and systems. Among them is dynamic tracking area management. Particularly, user equipment (UE) such as cell phones, laptop computers, wireless personal digital assistants, etc. are, by definition mobile and can move between cells over time. Accordingly, wireless communication networks typically have a technique or protocol for maintaining data on the locations of the user equipment for that network.
The LTE specification sets forth a protocol for maintaining data as to the locations of UEs on the network. Particularly, LTE provides for dynamic management of UE locations.
In this specification, a basic knowledge of LTE is assumed. In LTE, a UE interfaces to the network through an evolved node B (eNB). A Mobility Management Entity (MME) in the main signaling node in the network is responsible for initiating paging and authentication of UEs. It also maintains the location information of the UEs.
LTE introduces the concept of tracking areas (TAs). A tracking area is a subset of the volume of space within the wireless network in which any given UE may be located. A tracking area may comprise the area covered by one eNB (e.g., a cell) or multiple eNBs (multiple cells).
In accordance with the LTE specification, when a UE is idle (e.g., not in active communication over the network, such as on an active telephone call) the location of the UE is known at the MME on a granularity at the TA level. Each UE maintains a tracking area (TA) list which may comprise one or more TAs within which the UE is likely to be located. Only when the UE leaves the area covered by the TAs in its TA list does the UE initiate a tracking area update (TAU) operation to notify the MME of its new location. In response to a TAU, the MME typically returns an updated TA list to the UE.
In short, the tracking area update is a communication between the UE and the MME (e.g., through an eNB) informing the MME of the new tracking area of the UE. The MME also may transmit data to the UE in connection with tracking area management.
When a call is made to a UE (e.g., a voice call to a cellular telephone), the UE is paged by the network in the TAs in its last known assigned TA list. Consequently, if the UEs in a network tend to have larger TA lists, then the TAU traffic level should tend to be relatively low, but the paging traffic level should tend to be relatively higher. Particularly, the larger the number of TAs in the list, the more likely the UE will stay within the area covered by the TAs in its TA list. Therefore, it will need to perform TAUs less often. On the other hand, if the TA lists are kept relatively smaller, then there should be greater TAU traffic, but lesser paging traffic. Particularly, if a UE's TA list is small, then it is relatively more likely to leave the area covered by the TAs in the TA list, and, therefore, will need to perform TAUs more often. Further, because the number of TAs in the list is small, every time the UE is paged by the network, there are fewer TAs in which it potentially must be paged before it is located, thus tending to reduce paging traffic.
Prior generation wireless network technologies such as GSM (Global System for Mobile communication) utilized static routing area or location area management mechanisms, which presented a complex offline network design problem. Furthermore, even if well-engineered at the time of network design, changing network mobility characteristics over time during the operating lifetime of the network could quickly render the network design less than optimal for the given usage of the network. In addition, such static tracking area management mechanisms cannot be adapted to produce the optimal signaling load results for each individual UE. Therefore, regardless of changes in network mobility characteristics, the performance of a static tracking area management mechanism is still inferior to a dynamic tracking area management approach such as enabled by LTE.